The invention relates to a method in the reeling of a web, wherein the web is reeled by means of a first roll onto a second roll. When the second roll has reached the desired diameter size, a new reeling is started from the first roll onto a new second roll.
The invention also relates to a device for reeling a web from a first roll onto a second roll. When the second roll has reached a desired diameter size, the second roll is replaced by a new second roll onto which the web will be wound.
In the reel-up of a continuously operating paper machine, coating machine, or equivalent, when the reeled jumbo roll becomes full or reaches the desired size, the web will change from winding onto the full roll to winding onto an empty roll at full running speed of the paper machine, coating machine or equivalent. In such a case, reliability of operation is required in order that the operation of the machine is not interrupted from the cutting-off of the web and to its change onto the new roll.
A prior art method for the change of the web in a continuous reel-up is illustrated in FIGS. A1 and A2. As is shown in FIG. A1, a web P is reeled over a roll 111 onto a second roll 112. FIG. A1 is a schematic illustration of a situation in which the roll 112 has become full or reached the desired size. By means of a pin 115, a cut is made into the web P, and the web P starts to tear forming a wedge-shaped leading edge. Air is blown against the reeling cylinder by means of an air blow member 114 towards the web P after the nip formed by the new roll 110 and the reeling cylinder 111. At the cut made by the pin 115, the wedge-shaped leading edge, which is situated at the side of the arriving web P, is wound around the empty roll 110. The blow member 114 operates so that it also directs auxiliary blowings towards the sides of the web. These blowings cause the wedge-shaped leading edge to spread towards both edges of the web so that the web is torn.
However, in this prior art method, problems arise from the fact that the web is not always torn in the same way. The operation of the method is uncertain and may result in web breaks which require stopping the operation of the machine. It is a further limitation of this prior art method that it is only suitable for use with paper qualities of a weight lower than a certain grammage.
FIGS. B1 to B3 illustrate a second prior art method for changing the winding of a web in a continuous reel-up. In this prior art method, after the roll 112 has become full or reached the desired diameter, blowing is applied through the gap between the rolls by means of a blow member 116 from underneath the rolls 111 and 112. The web P starts forming a bag upwards. After the bag has become sufficiently large, it starts winding around a new empty roll 110. Finally, the web is broken and starts winding onto the new roll 110.
In this prior art method, the cutting-off of the web is uncontrolled. At the same time, owing to the slowness of the change process, the topmost layers on the full roll may become slack, which leads to a deterioration in the quality of the roll. Also, this prior art method is very noisy because of the high blow capacity that is required and, moreover, uncontrolled cutting-off of the web may cause standstills in the operation of the machine.
FIG. C illustrates a third prior art method in which to cut off the web and change it from a full roll 112, or from a roll of desired diameter, onto a new, empty roll 110, blowing is applied to the ends of the rolls. This blowing produces a tearing of the web P from the lateral direction and starts a winding of the web onto the empty roll 110. In this prior art method, controlled tearing of the web is unreliable, and may cause disturbance or standstills in the operation of the machine.